/Engine/Source/Editor/StaticMeshEditor/Public/StaticMeshEditorSubsystem.h
Add simple collisions to a static mesh. This method replicates what is done when invoking menu entries "Collision > Add [...] Simplified Collision" in the Mesh Editor.
An integer indicating the index of the collision newly created. A negative value indicates the addition failed.
int32 AddSimpleCollisionsWithNotification ( [UStaticMesh](API\Runtime\Engine\Engine\UStaticMesh) * StaticMesh, const EScriptCollisionShapeType ShapeType, bool bApplyChanges )